Gasoline or other liquid dispensing nozzles are commonly provided with vapor recovery systems to lessen the amount of volatile or otherwise undesirable vapor that escapes into the atmosphere when the liquid is dispensed. With specific reference to gasoline dispensing nozzles, such vapor recovery systems most commonly use a nozzle with a rubber bellows concentrically enclosing the spout. The space between the bellows and the spout is connected to a vacuum system, which draws in the vapors existing at the opening to the fill neck and prevents them from escaping and polluting the atmosphere.
Gasoline dispensing nozzles with bellows have certain practical limitations. The bellows are bulky, awkward, and expensive. The bellows also make it harder for users to insert and hold the spout in their vehicles' gasoline inlets. Bellowless nozzles have thus been proposed, as for example, in U.S. Pat. No. 4,351,375. A typical nozzle 10 of this type known in the art is depicted in FIG. 1. Such nozzles typically have coaxial inner and outer spouts 12, 14 of approximately circular cross-section. A vacuum system (not shown) is connected to space 16 between the inner and outer spouts in known manner. Vapor is drawn into this space through a plurality of holes 18 adjacent the distal end of the outer spout.
FIG. 2 depicts a typical motor vehicle gasoline inlet with vent tube. Gasoline tank 22 has main tube 24 connecting the tank to fill neck 26. A no-lead restriction plate 30 is located inside the fill neck, which has a circular opening 34 and a hinged trap door 37 sized to prevent users from inserting dispensing spouts of the larger size used for leaded gasoline. Coil spring 35 prevents the spout from entering the fill neck beyond the desired distance. There is also a vent tube 32, which allows vapor to escape from the top of the gas tank through opening 39. This tube allows vapors to escape from the tank without having to flow against the flow of gasoline pouring down the fill neck. Because opening 39 is on the gas tank side of restriction plate 30, the vapors vented through it can be drawn into nozzle 40 through holes 42.
In many vehicles, however, the gas tank vent tube does not open on the gas tank side of the restriction plate. Rather the tube opening is located on the side of the restriction plate opposite to the gas tank side. In this case, the known nozzle described above is unable to draw in the vapors because they are separated from its intake holes by the restriction plate. Such vapors are not recovered by existing bellowless gasoline dispensing nozzles.